Fig. 2

Identification of potential psychobiotics. a Percentage stacked graph showing phylum fractional abundances over time. Each ribbon represented a phylum. b Top ten genera relative abundance histogram. The top ten genera were selected on the basis of the mean relative abundances of each crew member. The genera relative abundance data of each subject is the average value from all time points. c Principal component analysis (PCA) score plots based on the relative abundance of gut microbiota at the individual and gender differences, respectively. d Horizon graphs of the variation of the scores of psychological factors over time. Horizon graphs are constructed by the median centering each psychological factor time series. The curve is divided into color bands, and its width is the median absolute deviation. Cooler and warmer regions indicate date ranges where a factor exceeds and below its median score, respectively. The darker the color, the higher the absolute value of the factor score. e Heatmap of Spearman’s correlation for potential psychobiotics and psychological factor scores. The potential psychobiotics whose correlation coefficient |R| was ≥ 0.5 (P < 0.001) in more than 50% of the psychological factors are shown here. The scaling of correlation coefficient is represented by color depth—a positive correlation is expressed in red and a negative correlation in blue. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001